1. Field of the Invention
The present invention relates to a method for cutting a liquid crystal display panel and, more particularly, to a method for cutting a plurality of liquid crystal display panels formed on large-scale mother substrates, and a method for fabricating a liquid crystal display panel using the same.
2. Description of the Related Art
As the consumers' interest in information displays grows and the demand for portable (mobile) information devices increases, research and commercialization of light and thin flat panel displays (“FPD”) has increased. Flat panel displays may replace the Cathode Ray Tube (“CRT”), which is the most common existing display device.
The liquid crystal display (“LCD”) device is a FPD device for displaying images by using optical anisotropy of liquid crystal. LCD devices exhibit excellent resolution and color and picture quality, so it is widely applied for notebook computers or desktop monitors, and the like.
The LCD device will now be described in detail.
The LCD device includes a liquid crystal display panel including a driving circuit unit, a backlight unit installed at a lower portion of the liquid crystal display panel and emitting light to the liquid crystal display panel, a mold frame for supporting the backlight unit and the liquid crystal display panel, and a case, etc.
With reference to FIG. 1, the liquid crystal display panel 10 includes an image display part 13 in which liquid crystal cells are arranged in a matrix form, a gate pad part 14 connected with gate lines 16 of the image display part 13 and a data pad part 15 connected with data lines 17.
The gate pad part 14 and the data pad part 15 are formed at an edge region of a thin film transistor (TFT) array substrate 1 that does not overlap with a color filter substrate 2. The gate pad part 14 supplies scan signals provided from a gate driver (not illustrated) to the gate lines 16 of the image display part 13, and the data pad part 15 supplies image information provided from a data driver (not illustrated) to the data lines 17 of the image display part 13.
Although not illustrated, the color filter substrate 2 includes a color filter including red, green and blue sub-color filters implementing colors, a black matrix for separating the sub-color filters and blocking light from transmitting through a liquid crystal layer, and a transparent common electrode for applying a voltage to the liquid crystal layer.
The array substrate 1 includes a plurality of gate lines 16 and a plurality of data lines 17 arranged vertically and horizontally thereon, respectively, and defining a plurality of pixel regions, the TFT, namely, a switching element, formed at each crossing of the gate lines 16 and the data lines 17, and a pixel electrode formed on each pixel region.
The array substrate 1 and the color filter substrate 2 are attached in a facing manner by a seal pattern 40 formed at an edge of the image display part 13 to form a liquid crystal display panel 10, and the two substrates 1 and 2 are attached through an attachment key (not illustrated) formed on the array substrate 1 or the color filter substrate 2.
In order to improve manufacturing yield, in the LCD device, the TFT array substrates are formed on a large-scale mother substrate, color filter substrates are formed on another separate mother substrate, which are then attached to simultaneously form the plurality of liquid crystal display panels. In this case, for the attached mother substrates, a cutting process is required to cut the attached mother substrates into a plurality of unit liquid crystal display panels.
In general, cutting of the mother substrates is performed such that a prearranged cut groove is formed on the mother substrates with a wheel with high hardness compared with glass and then cracking is made along the prearranged cutting groove.
FIG. 2 is a view illustrating the structure of a section of the unit liquid crystal display panel formed by attaching the first mother substrate on which the TFT array substrates are formed and the second mother substrate on which the color filter substrates are formed.
As illustrated, in the unit liquid crystal panels, the thin film transistor array substrates 1 are protruded at one side compared to the color filter substrates 2, because the gate pad part (not illustrated) and the data pad part (not illustrated) are formed at the edge portion of the thin film transistor array substrate 1 which is not overlapped with the color filter substrate 2.
Accordingly, the color filter substrates 2 formed on the second mother substrate 30 are formed to be separated as long as a first dummy region 31 corresponding to the protruded portion of the thin film transistor array substrates 1 formed on the first mother substrate 20.
The unit liquid crystal panels are suitably disposed such that the first and the second mother substrates 20 and 30 can be utilized to their maximum, and though they differ depending on a model, the unit liquid crystal panels are usually formed to be separated as long as a second dummy region 32.
After the first mother substrate 20 with the thin film transistor array substrates 1 formed thereon and the second mother substrate 30 with the color filter substrates 2 formed thereon are attached, the liquid crystal panels are cut. At this time, the first dummy region 31 formed at the portion where the color filter substrates 2 of the second mother substrate 30 are separated and the second dummy region 32 separating the unit liquid crystal panels are simultaneously removed.
The cutting process of the liquid crystal display panel will be described as follows.
FIG. 3 is an exemplary view illustrating a cutting process of the liquid crystal display panel.
As illustrated, a cutting device of the liquid crystal display panel includes a table 42 on which the first and second mother substrates 20 and 30 for which previous processes have been terminated, are loaded, and a cutting wheel 55 for processing the first and second mother substrates 20 and 30 to form prearranged cut lines 51.
In the cutting device of the liquid crystal display panel, when the first and second mother substrates 20 and 30 including a plurality of liquid crystal display panels and attached in a facing manner are loaded on the table 42, the cutting wheel 55 positioned at an upper side of the first and second mother substrates 20 and 30 is lowered and rotated in a state that certain pressure has been applied to the second mother substrate 30, to thereby form prearranged cut lines 51 in a groove form on the surface of the second mother substrate 30.
The prearranged cut lines are also formed on the first mother substrate 20. Namely, the first mother substrate 20 is processed with the cutting wheel 55 to form prearranged cut liens at the same positions as the prearranged cut lines 51 of the second mother substrate 30. Accordingly, in the liquid crystal panel cutting process, since the first and second mother substrates 20 and 30 are processed to form the prearranged cut lines 51, after the second mother substrate 30 is processed with the cutting wheel 55, the liquid crystal panel is reversed to make the first mother substrate 20 to face upward and then the first mother substrate 20 is processed with the cutting wheel 55.
Thereafter, pressure is applied to the prearranged cut lines 51 formed on the first and second mother substrates 20 and 30 to separate the first and second mother substrates 20 and 30. And then, the first and second mother substrates 20 and 30 are separated such that the first and second mother substrates 20 and 30 are stroke with a breaking bar so that cracking can be made along the prearranged cut lines 51.
In cutting the liquid crystal display panel, a scribing process and a breaking process are performed several times through a plurality number of reversing.
Thus, much time is required for the scribing process and the breaking process to cause a problem of reduction in productivity.
Furthermore, in the cutting method of the liquid crystal display panel, a plurality of glass chips are generated when the mother substrates are struck with a breaking bar to make cracks along the prearranged cut lines formed on the mother substrates. If the glass chips are adsorbed on the mother substrates, the quality of the LCD device would be degraded or the LCD device may not be driven.